AC Electric Railway Systems Research Articles

Harmonic mitigation of AC electric railway power feeding system by using single-tuned passive filters

Harmonic is an important factor affecting the quality of the power transmission system. caused by non-linear loads and power conversion devices. In this research, several train simulation samples of the city line Airport Rail Link (ARL) electric train were used to simulate the effects of harmonics on the power electric substation (ESS) by calculating the Total Harmonic Distortion of voltage (THDv) and current (THDi). Then compared with IEEE519-2014 standards to indicate the quality of power found that THDi 35th–50th exceeds the standard. In addition, the comparison of the harmonic reduction effect of the sample train from the single tuned passive filter designs of 3rd, 5th, 7th, and 11th showed that the 11th filter was able to keep the THD within the standard.

A Power Electronic Traction Transformer Model for a New Medium Voltage DC Electric Railway

All state-of-the-art Power Electronic Traction transformers (PETT) were developed for the existent Medium Voltage (MV) AC Electric Railway Systems (ERS). This work, however, presents a ...

New protective relay modeling scheme and analysis for AC electric railway feeding systems with Scott transformer

The Scott transformer is used in substations of the Korean AC electric railway system to convert a three-phase source to a single-phase source. The Scott transformer consists of two single-phase transformers and protects the M-phase and T-phase transformers with a single-phase protective relay. Percentage differential and overcurrent relays are used to provide primary and back-up protection to the Scott transformer. In this study, an overcurrent relay is used, and the protective relay is modeled using the Power System Computer Aided Design/Electromagnetic Transients program including DC (PSCAD/EMTDC). The inverse-time overcurrent relay present in the existing PSCAD/EMTDC will only change the coefficients in a given equation or use limited specifications with the default model. Unlike the existing element, which is limited when configuring the protection operating time, it is possible to obtain the operating time using a specific desired equation and coefficients through the modeled overcurrent relay. This overcurrent relay can be used to model the actual Korean AC electric railway system, and it is verified that the modeling approach that generates a fault in the feeding system is set based on comparison with numerical calculation. Based on this study, we developed a new modeling methodology for the overcurrent relay and for the Korean AC electric railway feeding system. In addition, no national or international standards exist that govern the protection standards for Scott transformers. Therefore, this study is expected to contribute considerably to the design and establishment of protection regulations for Scott transformers.

Overview of DC and AC Electric Railway Systems Considering Energy Efficiency Enhancement Methods

In this paper both DC and AC railway electric power feeding systems are reviewed and discussed. The advantage and disadvantage of these systems are also compared. One major problem of such systems is that they take the lion share of electricity consumption compared to non-traction systems. Therefore, most of the new technologies focus on enhancing Energy efficiency of railway systems. This paper discusses the main operation methodologies for reducing the consumption of electric traction systems. These methods include using renewable energy resources (RER), such as solar Photovoltaic (PV) panels and wind turbines, and regenerative braking. Moreover, the most common energy storage devices such as batteries, super-capacitors and flywheels. They are used in railway systems for storing the excess energy from RER or the return energy during regenerative braking (Batteries, super-capacitors and flywheel) are also explained. In addition, challenges of the right storage system selection for specific applications are briefly discussed.

교류전기철도 부하 불평형 개선을 위한 병렬형 능동형 밸런서 적용에 관한 연구

교류전기철도 부하 불평형 개선을 위한 병렬형 능동형 밸런서 적용에 관한 연구

Watt-Hour Metering Characteristics at Scott Transformer in AC Electric Railway Systems

Watt-Hour Metering Characteristics at Scott Transformer in AC Electric Railway Systems

Single-phase Cascaded H-bridge Multilevel Active Power Filters in AC Electric Railway Systems

The power quality of AC electric railways has become an issue worthy of more and more concern. Many active compensators based on power converters have been proposed, but with complex transformers or coupled branches. This paper presents a single-phase cascaded H-bridge multilevel active power filter (APF), which can directly connect to the 27.5-kV power supplies to deal with power quality problems. According to field measured data, the load characteristics are analyzed, and the system configuration and control system are designed based on the load characteristic analysis. Finally, simulation and experimental results verify the effectiveness of the proposed APF system, considering some problems such as the supply voltage fluctuations and transient inrush currents in AC electric railway systems.

Single‐phase cascaded H‐bridge multi‐level active power filter based on direct current control in AC electric railway application

A single-phase cascaded H-bridge multi-level active power filter (APF) to deal with the power quality problems in the AC electric railway systems is presented. The APF can connect to the traction busbar directly without any transformer or resonance branch. The direct current control combining the current decoupling transformation is introduced in the control strategy. This strategy simplifies the control system, enabling the least amount of current measurement with the existing sensors and removing complex current reference extraction algorithms. The control system design process, especially for the parameter tuning, is mainly discussed. Finally, simulation and experimental results verify the effectiveness of the proposed APF system applied in the AC electric railway systems.

선로변 전차선과 조가선의 전류를 이용한 집전성능 분석 기술

In this paper, analysis method for current collection performance based on real-time current of catenary system is proposed. An innovative method based on track-side of railway system is used for measurement of currents for overhead contact line during the collection with pantograph. The evaluation of a qualitative ratio for current collection performance were conducted using proposed algorithm under various conditions such as laboratory and track-side. To check the validity of our approach, we compared between calculation results from current of contact wire and measurement results from arcing of pantograph using simulator in laboratory conditions. The results show that the behavior of current collection performance were analysis from currents of overhead contact line in AC electric railway system.

A Novel Fault Location Scheme on Korean Electric Railway System Using the 9-Conductor Representation

This paper presents a novel fault location scheme on Korean AC electric railway systems. On AC railway system, because of long distance, 40[km] or above, between two railway substations, a fault location technique is very important. Since the fault current flows through the catenary system, it must be modeled exactly to analyze the fault current magnitude and fault location. In this paper, suggesting the novel scheme of fault location, a 9-conductor modeling technique including boost wires and impedance bonds is introduced based on the characteristics of Korean AC electric railway. After obtaining a 9-conductor modeling, the railway system is constructed for computer simulation by using PSCAD/EMTDC. By case studies, we can verify superiority of a new fault location scheme and propose a powerful model for fault analysis on electric railway systems.

Fault analysis of Korean AC electric railway system

This paper presents the fault analysis of Korean AC electric railway system. The AC electric railway system is modeled by PSCAD/EMTDC tool. This system model is composed of the Scott-transformer, the autotransformer, the running rails, the protection wires, the feeders, messenger wires and contact wires, etc. After obtaining the models of the fundamental elements describing Korean AC electric railway system, studies for the steady state and fault conditions are carried out. Simulation result and hand calculation for the fault analysis are compared with field data. Finally, we acquire the specific characteristic of Korean AC electric railway system. The proposed model would be a powerful tool for designing and planning Korean AC electric railway system.

Distribution of the traction return current in ac and dc electric railway systems

The problem of the determination of the real distribution of the return current in electric railway traction systems is considered. One or more conductors (depending on the specific supply system) are purposely set up to carry the traction return current flowing from the rolling stock axles back to the supply (i.e., substation); yet, part of the return current flows through signalling conductors (disturbing current) and through the earth, depending on the value of the electric parameters of the system, on the circuit arrangement, and on the relative position of the supply, the rolling stock, and signalling devices. The amplitude (as a percentage of the total return current) of the disturbing current may be high enough to cause interference to signalling. This work investigates the behavior of the return current in AC and DC electric railway systems, on the basis of a reference system for the variation of the most important electrical parameters. The definition of the transfer function between the return current and the signalling circuit variables is an important element for the compatibility analysis between train detection systems, rolling stock and infrastructure, to promote the cross-acceptance of rolling stock in Europe and abroad.

Distribution of the Traction Return Current in AC and DC Electric Railway Systems

The problem of the determination of the real distribution of the return current in electric railway traction systems is considered. One or more conductors (depending on the specific supply system) are purposely set up to carry the traction return current flowing from the rolling stock axles back to the supply (i.e., substation); yet, part of the return current flows through signalling conductors (disturbing current) and through the earth, depending on the value of the electric parameters of the system, on the circuit arrangement and on the relative position of the supply, the rolling stock and signaling devices. The amplitude (as a percentage of the total return current) of the disturbing current may be high enough to cause interference to signaling. This work investigates the behavior of the return current in ac and dc electric railway systems, on the basis of a reference system for the variation of the most important electrical parameters. The definition of the transfer function between the return current and the signalling circuit variables is an important element for the compatibility analysis between train detection systems, rolling stock and infrastructure, to promote the cross-acceptance of rolling stock in Europe and abroad.

Development of Static Var Compensator for San-yo Shinkansen.

This paper describes the application of SVC (Static Var Compensator) for the AC electric railway system, outlines the SVC installed at the Shin-syo sectioning post of San-yo Shinkansen and reports the results of a verification site investigation. A single-phase SVC can reduce the voltage drop in the feeding circuit and improve the power factor at substations by compensating for the reactive power. To compensate for the voltage drop, it is more effective to locate an SVC at a sectioning post than at a substation. The site investigation has revealed that an SVC can reliably suppress voltage drop.